89 k1500 TBI idle problems

Discussion in 'GM Powertrain' started by huggerOchevy, Jan 21, 2010.

  1. huggerOchevy

    huggerOchevy New Member

    Ok im new so if anybody could help me out id appreciate it..

    i just droped a remand jasper 350 in my
    truck and now the thing dosnt want to idle. some days it runs pretty good some days it runs like crap. i toped the new motor off with a brand new edelbrock preformer man, new distributer, plugs,wires,waterpump,iac valve an entire new fuel sending unit, fuel filter pretty much everything but the TBI its self is new under the hood... i warm it up in the morning, some days the idle is smooth as glass, some days the idle surges up and down to the point where it almost dies. i pull up to a stop light it does the same thing.. i have to keep a little bit of foot in the throttle to keep the idle up 95% of the time. ive shot the entire manifold with starter fluid to find and leaks, nothin, i cant hear the injectors surging, i cant find any vacume leaks and im about to go crazy. i dont know if its the map or what? anbody have any ideas?

  2. nos351wcm

    nos351wcm Rockstar

    The best thing you could do is take it to a shop and have it diagnosed. It could be a bad ground somewhere, faulty o2s or maybe a vacuum leak.
  3. ahm1127

    ahm1127 Rockstar 100 Posts

    Sounds like vacuum leak or ground as nos351wcm stated. Check your vacuum lines and base of TBI , also remove & retighten all ground wires with dialectric greese before you bring to shop.
  4. cwbontheyfz

    cwbontheyfz Rockstar


    take and unplug the vacuum hose to the egr and plug it with a nail or something and drive it for a couple days the check engine light will come on after a bit but that is a common problem that will cause different idle problems
  5. thattallguy32

    thattallguy32 New Member

    so many of these trucks are having similar problems, but everyone seems to have a different cause for it.

    personally on mine, the diaphragm pod on the back part of the TB was leaking gas, causing the computer to over-correct for it, by adding too much gas, then immediately cutting gas off due to there being too much being thrown in.
  6. 92WT

    92WT New Member

    Is not the diaphragm pod on the throttle body actually the fuel pressure regulator or are we talking about something else.
    I would agree that is the most likely cantidate considering everything you've replaced. Luckily its a fairly cheap kit (you need the kit for gaskets and seals) from the auto parts store. Just try to keep old gasket crap from falling down into things. O and bleed off fuel pressure first unless you want to wear it.
    Last edited: Feb 4, 2010
  7. 89classic

    89classic New Member

    I replaced my tps and erg valve and a set of hot ac deco rapidfires cause mine did the same now it's smooth. mine was doing the samething mines an 89 350.maybe test your coil or ign module.I put all performance ign parts on my 5.7.Just a thought.
    Last edited: Dec 25, 2010
  8. stephan

    stephan Rockstar 4 Years 5000 Posts

    That's good advice 89 Classic, & welcome to the GM truck club

    DAREDEVIL Rockstar 4 Years 1000 Posts

    WELCOME, i cant read that small sorry ...
  10. dualdj1

    dualdj1 Rockstar 100 Posts

    could be egr, or could be O2 sensor. O2's don't get read, and egr isn't kicked in, until the truck starts warming up, so either of those could easily be the culprit. Is it throwing any codes?

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